Methods for delivering active agents are of great interest. Various particles have been developed for storage and delivery of various active agents. Some particles are inorganic as described, for example, in Patent Application Publication WO 2006/135519 A1 (Finnie et al.). Other particles have a polymeric shell surrounding a hollow core that can be filed with active agents. Such particles are described, for example, in U.S. Patent Application Publication 2010/0104647 A1 (Ting) and U.S. Patent Application Publication 2011/0123456 (Pandidt et al.). Still other particles are hydrogels that swell when placed in contact with an active agent. Such hydrogels are described, for example, in WO 2007/146722 (Wright et al.).